KR101799073B1 - Viscous clutch valve assembly - Google Patents

Abstract

The valve assembly 26 for the bismuth clutch 20 includes an orifice plate 62 having a bore 60 formed therethrough that allows passage of fluid through the orifice plate 62, A reed valve 58, an armature 56 including a magnetic flux conducting material, an anchor spring 52 fixed to the armature 56, and a reinforcing plate 50. The reed valve 58 includes a tongue 58-1 configured to selectively cover the bore 60 of the orifice plate 62 and a first pivot position 58-4 along the tongue 58-1, . The first and second pivot positions 58-4, 52-1 are spaced from one another. An armature 56 is configured to selectively apply a force to the reed valve 58 to pivot at least a portion of the tongue 58-1 about the first pivot position 58-4.

Description

[0001] The present invention relates to a VISCUS CLUTCH VALVE ASSEMBLY,

The present invention relates generally to valves, and more particularly to electromagnetically actuated valves for use in biscuit clutches.

The Biscus Clutches are used in a wide variety of applications, such as fan drives in automotive applications. The clutch uses silicone oil to deliver torque between the two rotating components. This makes it possible to engage or disengage the clutch by allowing the entry and exit of oil into and out of the operating range of the clutch. The valve is used to control the oil flow between the input rotor and the output housing. A modern design is used that allows oil to be stored in the rotational input of the clutch while the clutch is disengaged to maintain kinetic energy available to allow rapid engagement of the clutch from an off condition. This also allows the clutch to have a very low output fan speed while in the off position. It has also become common for the clutch to be controlled electrically (i.e., electromagnetically). This is done to increase the controllability of the clutch and also to enable the clutch to respond to multiple cooling requests. Some of the possible cooling requirements are coolant temperature, intake air temperature, air conditioning temperature, and oil temperature.

However, the tolerances for the known biscuit clutches may be uncertain, for example, with reference to the flatness of the valve components providing fluid seals. For example, known valve assemblies using single-pivoted valve levers that do not have sufficient flatness may fail to provide a good seal to prevent viscous fluid from escaping from the reservoir to the operating area. In addition, known electromagnetically actuated valve assemblies may require a relatively large magnetic field for operation (i.e., to overcome the default spring biasing force), which undesirably results in a large electromagnetic coil You may need it. Large electromagnetic coils are relatively heavy, expensive and power-intensive.

Accordingly, alternate viscous clutches and associated valve assemblies are desirable.

A valve assembly for a bistable clutch according to an embodiment of the present invention includes an orifice plate having a bore formed therein for allowing passage of fluid through an orifice plate, a reed valve fixed to the orifice plate, An anchor spring fixed to the armature, and a reinforcing plate. The reed valve includes a tongue configured to selectively cover the bore of the orifice plate, and a first pivotal position along the tongue. A second pivotal position is formed along the anchor spring at the edge of the stiffening plate. The first and second pivot positions are spaced from each other. The armature is configured to selectively apply a force to the reed valve to pivot at least a portion of the tongue about the first pivot position.

1 is a cross-sectional view of a bismuth clutch according to the present invention,
Figure 2a is a perspective view of a portion of the bistable clutch of Figure 1 shown alone,
2B is a cross-sectional view of a portion of the biscuit clutch taken along line 2B-2B in Fig. 2A,
Figure 3 is a perspective view of the valve assembly of the bistable clutch of Figures 1 - 2b,
Figure 4 is an exploded perspective view of the valve assembly of Figure 3,
Figure 5 is a side view of the valve assembly of Figures 3 and 4,
Figures 6a and 6b are side elevation perspective views illustrating operation modeling of a valve assembly under a magnetic field, Figure 6a shows a valve assembly with a gusset omitted, and Figure 6b shows a valve assembly with a gusset.

While the foregoing drawings illustrate one or more embodiments of the invention, other embodiments may also be contemplated, as will be apparent from the discussion. In all cases, the disclosure of the present invention is intended to be illustrative rather than limiting. It should be understood that many other variations and embodiments within the scope and spirit of the principles of the present invention may be developed by those skilled in the art. The figures may not be drawn to scale.

Generally, the present invention relates to a valve assembly suitable for use in a biscuit clutch. For example, valve assemblies of the present invention are described in PCT Application Serial No. PCT / US2010 / 056659, filed November 15, 2010, each of which is incorporated herein by reference in its entirety and whose designation is "integral bismuth clutch & And is suitable for use in a bismuth clutch of the type disclosed in U. S. Patent Application No. 61 / 261,965, filed November 17, This application claims priority to U.S. Provisional Patent Application No. 61 / 375,173, filed on August 19, 2010, which is incorporated herein by reference in its entirety and entitled " A Biscuit Clutch Valve Assembly ".

Figure 1 shows an electromagnetic coil assembly 22, a rotor 24, a valve assembly 26, a first bearing set 28, a shaft (or bracket) 30, a second bearing set 32, a retaining member 34 , A reservoir 36, an input member 38 (e.g., a sheave), and an output member 40. The biscuit clutch 20 includes a biscuit clutch 20, The input member 38 receives the input force (e.g., torque from the belt) and transmits the force (power) to the rotor 24. The output member 40 is adjacent to the rotor 24, and a working chamber is defined therebetween. In the embodiment shown in FIG. 1, the output member 40 has a multi-part construction with separate housing 40A and cover 40B parts secured to one another and at least partially surrounding the rotor 24. A fan or other component (not shown) may be coupled to the output member 40 and rotated with the output member. The shaft 30 supports the components of the clutch with respect to the mounting position and is rotatably fixed. Suitable spacers, sleeves, etc. may be positioned on the shaft 30, if desired, to aid in the retention of, for example, the bearing sets 28,32. The shaft 30 allows the clutch 20 to be mounted in a desirable position, such as inside the engine compartment of an automobile (not shown). The shaft 30 can not be fixed or rotated (although it should be understood that the fixed components of the clutch 20 can be installed in a vehicle). A retaining member 34 (e.g., a toothed nut) aids in supporting the components on the shaft 30. During operation, a viscous fluid (or a shear fluid), which may be a conventional form (e.g., silicone oil), may be selectively introduced into the operating chamber so that torque is transmitted to the rotor 24 and the output member 40). The return path (e.g., suitable paths through the output member 40) allows viscous fluid to return from the operating chamber to the reservoir 36 in a conventional manner. The reservoir 36 may hold some or all of the shear fluid and the valve assembly 20 may selectively control the transfer of shear fluid from the reservoir 36 to the operating chamber.

2A to 5 show portions of the bismuth clutch 20. Figure 2a is a perspective view of a portion of the biscuit clutch 20, Figure 2b is a cross-sectional view of a portion of the biscuit clutch 20 taken along line 2B-2B in Figure 2a, Figure 3 is a perspective view of the valve assembly 26, 4 is an exploded perspective view of the valve assembly 26, and Fig. 5 is a side view of the valve assembly 26. Fig.

The valve assembly 26 includes a stiffening plate 50, an anchor spring 52, a back plate 54, an armature 56, and a reed valve 58. The valve assembly 26 controls the flow of viscous fluid through the bore 60 in the orifice plate 62, which provides a fluid path from the reservoir 36 to the operating chamber. The selective energization and non-activation of the electromagnetic coil assembly 22 controls the operation of the valve assembly 26 such that it can be spring biased to its default position when the electromagnetic coil assembly 22 is non- And then moved to another position when the electromagnetic coil assembly 22 is activated. In the illustrated embodiment, the valve assembly 26 is spring biased to an "open" position by default, where the bore 60 is opened to allow viscous fluid to flow from the reservoir 36 to the operating chamber.

As shown in the embodiment of FIG. 1, the valve assembly 26 is generally located between the electromagnetic coil 22 and the rotor 24. The valve assembly 26 can be submerged in a reservoir 36 and attached to a rotor 24 that rotates with an input member 38 at an input speed and can be carried by the rotor 24.

The valve assembly 26 includes two independent pivoted (or contoured) subassemblies that help to make the overall valve assembly 26 more flexible. The first valve subassembly includes an anchor spring 52 and an armature 56 (the gusset plate 50 and the back plate 54 may also be considered as part of the first valve subassembly). The second valve subassembly includes a reed valve (58). The armature 56 may be pivoted about the reed valve 58 and in contact with the reed valve 58 (e.g., by a magnetic field, a spring force, etc.), which in turn is transmitted by the armature 56 Lt; / RTI > The reed valve 58 then restricts or prevents viscous fluid from passing from the reservoir 36 through the orifice plate 62 by being pressed against the orifice plate to cover and at least partially seal the bore 60. In this manner, the armature 56 slides relative to the reed valve 58 during operation so that the armature 56 and the reed valve 58 are in their respective pivot positions (as will be further described hereinafter) For example, fulcrum, bending positions, or hinges). The formation of the seal can be facilitated when the anchor spring 52 is axially offset from the actual plane formed by the side of the reed valve 58 towards the armature 56. [ The tolerance for the flatness of the armature 56 for the machining of the rotor 24 with the anchor spring 52 and the orifice plate 62 mounted thereon is therefore fixed directly to the armature and can be moved together with the armature, But may be less restrictive for prior art systems with only a single valve lever being formed (monolithically).

The present invention also provides control of the spring rate of the valve assembly 26. The anchor spring 52 contributes to the spring constant of the valve assembly 26. The anchor spring 52 connects the fixed (i.e., non-pivotable) rotor-mount portion of the valve assembly 26 to the dynamic (i.e., pivotable) first valve subassembly. The anchor springs 52 may be interposed between (and in contact with) the stiffening plate 50 and the rotor 24 and may be connected to suitable fasteners 64 (e.g., bolts, screws, rivets) And can also be attached to the armature 56 at the opposite end by suitable fasteners 66 (e.g., bolts, screws, rivets). The anchor spring may be located generally opposite the reed valve 58 in the valve assembly 26. In one embodiment, the anchor spring 52 may be made of spring steel (e.g., ASTM A109-03).

The primary function of the stiffening plate 50 is to assist in controlling the spring constant of the valve assembly 26. The pivot position 52-1 of the anchor spring 52 is defined along the armature-oriented edge of the stiffener plate 50. Control of the spring constant is achieved by controlling the clearance L between the armature 56 and the stiffening plate 50 so that the valve assembly 26 can be moved to the rotor 24 by a calibrated assembly anchoring device Anchoring can be easily controlled during the fabrication process. It should also be noted that the width W of the gusset plate 50 (which can produce an inversely proportional change of the gap L) Can be achieved through changes. In this way, the valve assembly 26 is modular and can be used to modify the stiffening plate 50 (and / or the back plate 54) while allowing for reuse of some or all of the remaining components of the valve assembly 26 Can be adjusted for the application. The stiffening plate 50 may be made of a metallic material and may be configured to be relatively rigid rather than flexible, such as an anchor spring 52. In the illustrated embodiment, the stiffening plate 50 is substantially thicker than the anchor springs 52 to increase stiffness.

The rear plate 54 is provided with the following functions: (1) control of the deformation shape of the anchor spring 52, (2) the function of the anchor spring 52 (in relation to the rotation axis of the clutch 20) (3) a function of providing additional torsional strength, as will be described in greater detail below. With respect to item (1) described above, the anchor spring 52 can form an undesirably "S" shape under the influence of the magnetic force without the back plate 54, as shown in Fig. 6A. 6b, the rear plate 54 is configured such that the deformed shape of the anchor spring 52 has a cantilever bend shape (i.e., "S" shape) between the armature 56 and the stiffening plate 50 Such as a cantilevered beam loaded at the distal end / free end, rather than in multiple directions). In other words, the back plate 54 supports the axial translation of the armature 56, which may occur in association with the bending of the anchor plate 52 into a complicated shape, which encourages pivoting movement of the armature 56 ) In the direction of the axis of rotation). In the illustrated embodiment, the back plate 54 is located on the first side of the anchor spring 52, the opposite side of the stiffening plate 50. The back plate 54 may extend along the side of the anchor spring 52 from the edge of the first extension 56-2 of the armature 56 toward the pivot position 52-1. In the illustrated embodiment, the back plate 54 extends beyond the pivot position 52-1 of the anchor spring 52 such that the back plate 54 and the stiffening plate 50 are generally radially partially (The amount of redundancy can be varied if desired for a particular application). This configuration of the valve assembly 26 limits or prevents the first extension 56-2 of the armature 56 from being pulled in the axial direction and prevents the torsional strength 26 when the armature 56 is pulled toward the electromagnetic coil assembly 22. [ In the United States. The back plate 54 may be attached to the armature 56 and the anchor spring 52 at one end and may be detached from the anchor spring 52 at the opposite end and still provide the same functions as above. The back plate 54 may be made of a metallic material and may be configured to have relatively stiffness rather than flexibility, such as an anchor spring 52. In the illustrated embodiment, the back plate 54 is substantially thicker than the anchor spring 52 to increase strength.

The armature 56 is a movable part and can be activated or moved by a magnetic field created by the electromagnetic coil assembly 22 to form a portion of the magnetic flux path for the magnetic field generated by the coil assembly 22. [ The armature 56 may be made of a magnetic flux conducting material operable by a magnetic field, such as a low carbon steel.

In operation, the armature 56 is pulled axially toward the electromagnetic coil assembly 22 by a magnetic field when the electromagnetic coil assembly 22 is activated. The armature 56 assists magnetic flux transfer for electromagnetic flux from the electromagnetic coil assembly 22 to the armature 56 and from the armature 56 to the shaft 30 (with the magnetic flux finally returning to the coil assembly 22) . When the armature 56 is pulled toward the electromagnetic coil assembly 22 the reed valve covers the bore in the orifice plate 62 to slow the flow of viscous fluid from the reservoir 36 to the working chamber of the biscuit clutch 20 Or stop the reed valve (58). 3), the armature 56 includes a generally annular body portion 56-1, an elongated body portion 56-1 extending from the body portion 56-1 and having an anchor spring 52 and a rear plate 54, And a second extension portion 56-3 extending from the main body portion and configured to contact the reed valve 58. The first extension portion 56-2 includes a first extension portion 56-2 and a second extension portion 56-3. A pair of tabs 56-4, 56-5 extending from the body portion 56-1 may also be provided. In the illustrated embodiment, the first and second extensions 56-2, 56-3 are positioned approximately 180 degrees from each other, and the tabs 56-4, 56-5 are positioned approximately 180 degrees from each other And the first extension portion 56-2 is positioned at approximately 90 [deg.] From the tab 56-4. The armature 56 may be a relatively rigid member that is not adequately flexible, i.e., does not form a pivotal position or hinge during operation so that the armature is generally substantially planar, irrespective of the applied electric field, , The planar shape can be maintained.

The reed valve 58 is located between the rotor 24 and the orifice plate 62. In the illustrated embodiment, the reed valve 58 is a generally "T" shaped with a tongue portion 58-1 and a pair of legs 58-2, 58-3. In a further embodiment, the reed valve 58 may be in the shape with three legs (i.e., "W", "M", or "E"). The tongue 58-1 may form a pivotal position 58-4 at a spaced location between opposite ends of the tongue 58-1. Also, the distal end of the cantilevered tongue 58-1 can be larger than the adjacent region of the tongue 58-1, thus facilitating the covering and sealing of the bore 60. [ The distal end of the tongue 58-1 may be pivoted about the pivot position 58-4 to cover or open the bore 60. [ The legs 58-2 and 58-3 may be arranged at the proximal end of the tongue (i.e., opposite the distal end) and suitable fasteners (e.g., bolts, rivets, screws) ) To the orifice plate (62). In one embodiment, the reed valve 58 may be made of spring steel (e.g., ASTM A109-03). The reed valve 58 may optionally assist in providing a seal for the orifice plate 62 when the armature 56 is pulled toward the electromagnetic coil assembly 22. [ In particular, the second extension 56-3 of the armature 56 is located on the reed valve 58 when the armature 56 is urged against the reed valve 58 to cover the bore 60 in the orifice plate 62, Of the tongue 58-1. The reed valve 58 also helps maintain the overall spring constant of the valve assembly 26 to a minimum while opening the valve assembly 26 at a faster rate than prior art cantilever systems 62). ≪ / RTI > The valve assembly 26 of the present invention may provide at least a portion of a quicker opening (i.e., opening of the bore 60) because the spring forces of both the reed valve 58 and the anchor spring 52, Which helps to press the armature 56 away from the assembly 22 and allows the reed valve 58 to be moved away from the pivot position 52-1 of the anchor spring 52 by a second extension of the armature 56 Since the portion 56-3 can be deflected, thereby obtaining a mechanical advantage in the deflection torque.

In the illustrated embodiment, the pivot position 58-4 is spaced from the pivot position 52-1, and these pivot positions are on opposing sides of the rotational axis of the clutch, opposite each other across the shaft 30. [ Lt; / RTI > Pivot position 58-4 and pivot position 52-1 are fixed relative to each other in the illustrated embodiment, and the spacing between these components does not change during clutch operation.

The orifice plate 62 is mounted adjacent the reed valve 58 and may be attached to the rotor 24 (or other suitable mounting structure). In some embodiments, legs 58-2 and 58-3 may be interposed between portions of orifice plate 62 and rotor 24. In the illustrated embodiment, the orifice plate 62 is mounted to the protrusions of the rotor 24 by suitable fasteners 70 (see FIG. 1) and the tongue 58-1 of the reed valve 58 is connected to the orifice Spacers or grooves 72 are provided along the rotor 24 so as to be movable within a region located between the plate 62 and the rotor 24. The design of the orifice plate 60 may be modified to vary the size of the bore 60 (i.e., orifice) if desired for a particular application. This configuration enhances the modularity of the valve assembly 26 because the bore 60 in the orifice plate 62 can be adapted to particular applications without the need to modify the remaining components of the valve assembly 26. [

The orifice plate 62 further comprises a recess 73 along the rotor-facing surface (see FIGS. 4 and 5), which recess is defined by at least a portion of the tongue 58-1 of the reed valve 58 . In particular, a portion of the tongue 58-1 near the pivot position 58-4 can be aligned with the recess 73 at a spaced position between opposite ends of the tongue 58-1. The recesses 73 help to promote the movement of the reed valve 58 and also cause undesirable static friction (i.e., sticking between the components that can be exacerbated by the presence of viscous fluid) Helps to reduce the contact area between the tongue 58-1 and the orifice plate 62 to help reduce it.

The orifice 62 may also provide a stop surface for the reed valve 58 and armature 56. Throughout the low ambient conditions, the orifice plate 62 can help prevent the armature 56 from contacting the electromagnetic coil assembly 22.

The clutch 20 may further include a stop 74 wherein the stop 74 is provided adjacent each of the tabs 56-4 and 56-5 of the armature 56. [ The stops 74 are configured to limit the movement of the armatures 56 as well as the tabs 56-4, 56-5 under any operating conditions. The stops 74 can be fixed to the rotor 24, respectively, for example, by suitable fasteners 76 (e.g., bolts, screws, rivets). In the illustrated embodiment, the rotor-oriented surface of each stop 74 is a rotor-oriented surface of the orifice plate 62 adjacent the second extension 56-3 of the armature 56 by a gap G, (I.e., in a non-coplanar relationship with the rotor-oriented surface), so that the rotor-oriented surfaces of the stop 74 may be offset from the rotor ' - more distant from the rotor 24 in the axial direction than the oriented surface. This configuration is advantageous, for example, in low ambient temperature conditions where the coil assembly 22 is operated at a relatively high arm pair and tends to generate a relatively large magnetic field, at least one of the tabs 56-4, 56-5 Allowing the stop portions 74 to limit the movement of the armature 56 when it contacts the corresponding stop portion 74 under high force conditions. Stopping or restricting the movement of the armature 56 helps to reduce the risk of damage to the reed valve 58 due to excessive movement of the armature 56 while the offset gap G causes the stops 74 and / Tabs 56-4 and 56-5 help to reduce the risk of hindering normal valve operation under normal operating conditions.

Those skilled in the art will recognize that the invention provides many advantages and benefits. For example, the valve assembly of the present invention has a relatively low spring constant, which allows the use of relatively small electromagnetic coils. Relatively small forward coils can operate at relatively low power levels. The valve assembly of the present invention also provides a relatively high control over the flatness tolerance of the seating components to provide a relatively good sealing contact when the valve assembly is positioned to limit or prevent fluid flow Help. Other features of the present invention help to reduce the risk of damage to the valve assembly under high electromagnetic force conditions typically present, for example, at relatively low operating temperatures. Other features and advantages will be apparent to those skilled in the art in view of this description of the invention.

The terms of any relative terms or degrees used herein, such as "substantially,""approximately,""essentially,""generally," and the like, And should be interpreted to be subordinate to them. In all instances, any relative terms or degrees of terminology used herein are intended to be construed in a manner that is consistent with the understanding of the ordinary skill in the art in view of the full context of this description, including, It is to be interpreted that the scope of the present invention is broadly encompassed not only by any of the above-mentioned related embodiments, but also by its ranges or modifications.

While the present invention has been described with reference to exemplary embodiments (s), it is to be understood that many changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention Will be understood by those skilled in the art. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, the invention is not limited to the specific embodiments (s) described above, and the invention will include all embodiments falling within the spirit and scope of the description. For example, one or more equivalent structures may be added to the valve assembly in other embodiments

. The relative shapes and sizes of the described components may vary if desired for particular applications. Also, the stiffening plate and / or the backing plate may be omitted in some embodiments. Furthermore, the features of any of the foregoing embodiments may be utilized in any of the other foregoing embodiments, as long as they are desirable for particular applications.

Claims (25)

As the bismuth clutch,
An input member for receiving input torque,
A rotor fixed to the input member to rotate with the input member,
An output member positioned adjacent the rotor,
An operating chamber formed between the rotor and the output member,
A reservoir configured to hold a shear fluid,
A return passage formed between the operating chamber and the reservoir,
An electromagnetic coil for selectively generating a magnetic field, and
And a valve assembly configured to selectively control the flow of shear fluid between the reservoir and the working chamber,
An orifice plate on which a bore is formed to allow passage of the shear fluid through the orifice plate,
A tongue portion configured to selectively cover the bore of the orifice plate; and a first pivot position (58-4) through which the distal end of the tongue can be pivoted along the tongue, A reed valve,
An armature configured to selectively apply a force to the reed valve in response to a function of a magnetic field generated by the electromagnetic coil to pivot at least a distal end of the tongue about the first pivot position; ,
An anchor spring fixed to the armature, and
And a reinforcing plate,
A second pivot position (52-1) is formed in the stiffening plate along the anchor spring at the edge of the stiffening plate, the first and second pivot positions being spaced from each other,
Biscuit clutch.
The method according to claim 1,
Wherein the anchor spring and the orifice plate are secured to the rotor such that the valve assembly is rotatable with the rotor,
Biscuit clutch.
The method according to claim 1,
And a stopper fixed to the rotor,
Wherein the stop is configured to limit movement of the armature towards the electromagnetic coil,
Biscuit clutch.
The method according to claim 1,
The armature
A body portion, and
And an extension from said body portion,
Wherein the extension portion is configured to contact the tongue portion of the reed valve in operation,
Biscuit clutch.
5. The method of claim 4,
The armature
Further comprising a tab extending from said body portion by 90 degrees from said extension,
Biscuit clutch.
The method according to claim 1,
The valve assembly includes:
Further comprising a back plate secured to the anchor spring and extending along a first side of the anchor spring from an edge of the armature toward the second pivot position,
Biscuit clutch.
The method according to claim 6,
Wherein the back plate at least partially overlaps the reinforcing plate,
Biscuit clutch.
The method according to claim 1,
Wherein the reinforcing plate is spaced apart from the armature by a gap L,
Biscuit clutch.
The method according to claim 1,
Further comprising a fixed shaft, the output member and the input member being rotatably supported by the fixed shaft,
Biscuit clutch.
10. The method of claim 9,
Wherein the electromagnetic coil is located within the reservoir,
Biscuit clutch.
As a method of operating the biscuit clutch,
Biasing a reed valve uncovered by default by spring deflection,
Generating a magnetic field,
Pivoting the armature about a first pivot position (52-1) using the magnetic field,
Applying a force to the reed valve by the armature while the magnetic field is being generated, the armature pressing the reed valve as the force is applied, and as the force is applied, Applying a force to the reed valve to slide along the valve,
Pivoting at least a portion of the reed valve about a second pivot position (58-4) spaced from the first pivot position in accordance with a function of an applied force, and
And covering the bore with a reed valve to limit fluid flow therethrough while the magnetic field is generated.
A method of operating a biscuit clutch.
delete 12. The method of claim 11,
Further comprising restricting bending of an anchor spring attached to the armature by a back plate, wherein the first pivot position is formed by the anchor spring,
A method of operating a biscuit clutch.
12. The method of claim 11,
Further comprising the step of forming a position of said first pivot position along an anchor spring attached to said armature using an edge of a stiffening plate positioned in contact with an anchor spring, said edge of said stiffening plate being spaced from said armature,
A method of operating a biscuit clutch.
15. The method of claim 14,
Further comprising changing a width of the reinforcing plate to adjust a spring constant of the anchor spring,
A method of operating a biscuit clutch.
A valve assembly for a bismuth clutch,
An orifice plate having a bore formed therethrough for allowing passage of the fluid through the orifice plate,
A reed valve including a tongue configured to selectively cover the bore of the orifice plate and a first pivot position along the tongue, the reed valve being secured to the orifice plate,
An armature configured to selectively apply a force to the reed valve to pivot at least a portion of the tongue about the first pivot position;
An anchor spring fixed to the armature, and
And a reinforcing plate,
A second pivot position (52-1) is formed in the stiffening plate along the anchor spring at the edge of the stiffening plate, the first and second pivot positions being spaced from each other,
Valve assembly for a biscuit clutch.
17. The method of claim 16,
The armature
A body portion, and
And an extension from said body portion,
Wherein the extension portion is configured to contact the tongue portion of the reed valve in operation,
Valve assembly for a biscuit clutch.
18. The method of claim 17,
The armature
Further comprising a tab extending from said body portion by 90 degrees from said extension,
Valve assembly for a biscuit clutch.
17. The method of claim 16,
Further comprising a back plate secured to the anchor spring and extending along a first side of the anchor spring from an edge of the armature toward the second pivot position,
Valve assembly for a biscuit clutch.
20. The method of claim 19,
Wherein the back plate at least partially overlaps the reinforcing plate,
Valve assembly for a biscuit clutch.
17. The method of claim 16,
Wherein the reinforcing plate is spaced apart from the armature by a gap L,
Valve assembly for a biscuit clutch.
17. The method of claim 16,
Wherein said orifice plate includes a recessed portion oriented toward said reed valve, said first pivoted position being aligned with said recessed portion,
Valve assembly for a biscuit clutch.
As the bismuth clutch,
An electromagnetic coil for selectively generating a magnetic field,
A valve assembly configured to selectively control a flow of shear fluid between the reservoir and the working chamber through the bore according to a function of the magnetic field generated by the electromagnetic coil; And
The valve assembly comprising:
A first valve subassembly including an armature configured to pivot about a first pivot position (52-1), and
A second valve subassembly including a reed valve,
Wherein at least a portion of the reed valve is configured to pivot about a second pivot position (58-4) spaced from a first pivot position, the first valve subassembly having a force such that the reed valve selectively covers the bore To the second valve subassembly,
Wherein the valve assembly is carried by a rotor,
Biscuit clutch.
24. The method of claim 23,
The first valve subassembly
An anchor spring fixed to the armature, and
And a reinforcing plate,
Wherein a first pivot position is formed along the anchor spring at the edge of the stiffening plate and the first and second pivot positions are spaced from each other,
Biscuit clutch.
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